On Thu, Apr 11, 2019 at 01:50:43PM -0400, Joel Fernandes (Google) wrote: > Other than verifying pidfd based polling, the tests make sure that > wait semantics are preserved with the pidfd poll. Notably the 2 cases: > 1. If a thread group leader exits while threads still there, then no > pidfd poll notifcation should happen. > 2. If a non-thread group leader does an execve, then the thread group > leader is signaled to exit and is replaced with the execing thread > as the new leader, however the parent is not notified in this case. > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > --- > tools/testing/selftests/pidfd/Makefile | 2 +- > tools/testing/selftests/pidfd/pidfd_test.c | 216 ++++++++++++++++++++- > 2 files changed, 208 insertions(+), 10 deletions(-) > > diff --git a/tools/testing/selftests/pidfd/Makefile b/tools/testing/selftests/pidfd/Makefile > index deaf8073bc06..4b31c14f273c 100644 > --- a/tools/testing/selftests/pidfd/Makefile > +++ b/tools/testing/selftests/pidfd/Makefile > @@ -1,4 +1,4 @@ > -CFLAGS += -g -I../../../../usr/include/ > +CFLAGS += -g -I../../../../usr/include/ -lpthread > > TEST_GEN_PROGS := pidfd_test > > diff --git a/tools/testing/selftests/pidfd/pidfd_test.c b/tools/testing/selftests/pidfd/pidfd_test.c > index d59378a93782..4d5206280091 100644 > --- a/tools/testing/selftests/pidfd/pidfd_test.c > +++ b/tools/testing/selftests/pidfd/pidfd_test.c > @@ -4,18 +4,26 @@ > #include <errno.h> > #include <fcntl.h> > #include <linux/types.h> > +#include <pthread.h> > #include <sched.h> > #include <signal.h> > #include <stdio.h> > #include <stdlib.h> > #include <string.h> > #include <syscall.h> > +#include <sys/epoll.h> > +#include <sys/mman.h> > #include <sys/mount.h> > #include <sys/wait.h> > +#include <time.h> > #include <unistd.h> > > #include "../kselftest.h" > > +#define CHILD_THREAD_MIN_WAIT 3 /* seconds */ > +#define MAX_EVENTS 5 > +#define __NR_pidfd_send_signal 424 > + > static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info, > unsigned int flags) > { > @@ -30,6 +38,22 @@ static void set_signal_received_on_sigusr1(int sig) > signal_received = 1; > } > > +static int open_pidfd(const char *test_name, pid_t pid) > +{ > + char buf[256]; > + int pidfd; > + > + snprintf(buf, sizeof(buf), "/proc/%d", pid); > + pidfd = open(buf, O_DIRECTORY | O_CLOEXEC); > + > + if (pidfd < 0) > + ksft_exit_fail_msg( > + "%s test: Failed to open process file descriptor\n", > + test_name); > + > + return pidfd; > +} > + > /* > * Straightforward test to see whether pidfd_send_signal() works is to send > * a signal to ourself. > @@ -87,7 +111,6 @@ static int wait_for_pid(pid_t pid) > static int test_pidfd_send_signal_exited_fail(void) > { > int pidfd, ret, saved_errno; > - char buf[256]; > pid_t pid; > const char *test_name = "pidfd_send_signal signal exited process"; > > @@ -99,17 +122,10 @@ static int test_pidfd_send_signal_exited_fail(void) > if (pid == 0) > _exit(EXIT_SUCCESS); > > - snprintf(buf, sizeof(buf), "/proc/%d", pid); > - > - pidfd = open(buf, O_DIRECTORY | O_CLOEXEC); > + pidfd = open_pidfd(test_name, pid); > > (void)wait_for_pid(pid); > > - if (pidfd < 0) > - ksft_exit_fail_msg( > - "%s test: Failed to open process file descriptor\n", > - test_name); > - > ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0); > saved_errno = errno; > close(pidfd); > @@ -368,10 +384,192 @@ static int test_pidfd_send_signal_syscall_support(void) > return 0; > } > > +void *test_pidfd_poll_exec_thread(void *priv) I think you can do static here? > +{ > + char waittime[256]; > + > + ksft_print_msg("Child Thread: starting. pid %d tid %d ; and sleeping\n", > + getpid(), syscall(SYS_gettid)); > + ksft_print_msg("Child Thread: doing exec of sleep\n"); > + > + sprintf(waittime, "%d", CHILD_THREAD_MIN_WAIT); > + execl("/bin/sleep", "sleep", waittime, (char *)NULL); > + > + ksft_print_msg("Child Thread: DONE. pid %d tid %d\n", > + getpid(), syscall(SYS_gettid)); You execl(), but then print stuff after that? Might also be worth switching to execlp(). > + return NULL; > +} > + > +static int poll_pidfd(const char *test_name, int pidfd) > +{ > + int c; > + int epoll_fd = epoll_create1(0); A style point, but I find it's best not to do resource allocation in variable declarations like this. It breaks up the usual pattern of: ret = -ENOMEM; resource = allocate(); if (allocation_failed(resource)) goto err; ... out: free(resource); err: return ret; You're not closing this fd on every path (they all exit [for now :D] so it's probably ok), but it might be nice to make this match a more regular pattern. > + struct epoll_event event, events[MAX_EVENTS]; > + > + if (epoll_fd == -1) > + ksft_exit_fail_msg("%s test: Failed to create epoll file descriptor\n", > + test_name); > + > + event.events = EPOLLIN; > + event.data.fd = pidfd; > + > + if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, pidfd, &event)) { > + ksft_print_msg("%s test: Failed to add epoll file descriptor: Skipping\n", > + test_name); Might be worth checking errno == EPERM here too (which according to the man page is the error for "epoll not supported", which is weird :). > + _exit(PIDFD_SKIP); > + } > + > + c = epoll_wait(epoll_fd, events, MAX_EVENTS, 5000); > + if (c != 1 || !(events[0].events & EPOLLIN)) > + ksft_exit_fail_msg("%s test: Unexpected epoll_wait result (c=%d, events=%x)\n", > + test_name, c, events[0].events); > + > + close(epoll_fd); > + return events[0].events; > + > +} > + > +int test_pidfd_poll_exec(int use_waitpid) I think this can be static too. > +{ > + int pid, pidfd; > + int status, ret; > + pthread_t t1; > + time_t prog_start = time(NULL); > + const char *test_name = "pidfd_poll check for premature notification on child thread exec"; > + > + ksft_print_msg("Parent: pid: %d\n", getpid()); > + pid = fork(); > + if (pid == 0) { > + ksft_print_msg("Child: starting. pid %d tid %d\n", getpid(), > + syscall(SYS_gettid)); > + pthread_create(&t1, NULL, test_pidfd_poll_exec_thread, NULL); > + /* > + * Exec in the non-leader thread will destroy the leader immediately. > + * If the wait in the parent returns too soon, the test fails. > + */ > + while (1) > + ; > + } > + > + ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid); > + > + if (use_waitpid) { > + ret = waitpid(pid, &status, 0); > + if (ret == -1) > + ksft_print_msg("Parent: error\n"); > + > + if (ret == pid) > + ksft_print_msg("Parent: Child process waited for.\n"); > + } else { > + pidfd = open_pidfd(test_name, pid); > + if (poll_pidfd(test_name, pidfd) & EPOLLERR) > + ksft_exit_fail_msg("%s test: Unexpected epoll error\n", test_name); > + } > + > + time_t prog_time = time(NULL) - prog_start; > + > + ksft_print_msg("Time waited for child: %lu\n", prog_time); > + > + /* Check to make sure poll_pidfd returns error after reaping */ > + if (!use_waitpid && > + (waitpid(pid, &status, 0) != pid || !(poll_pidfd(test_name, pidfd) & EPOLLERR))) { > + ksft_exit_fail_msg("%s test: poll_pidfd EPOLLERR check failed\n", test_name); > + } > + close(pidfd); > + > + if (prog_time < CHILD_THREAD_MIN_WAIT || prog_time > CHILD_THREAD_MIN_WAIT + 2) > + ksft_exit_fail_msg("%s test: Failed\n", test_name); > + else > + ksft_test_result_pass("%s test: Passed\n", test_name); > +} > + > +void *test_pidfd_poll_leader_exit_thread(void *priv) Another static I think? Tycho